Video Recording with DSLR - how large memory card needed?

eager to learn

Hi,

I'm a newbie.

I have a Canon DSLR Rebel EOS 5.

I have a 16 GB memory card for it.

I want to record a video of a small workshop (20 attendees) this weekend.

Will I have enough memory to record the 2 hour workshop?

Will I need to record at 1080/60p (highest quality - I've read)?

Can I set the camera to another setting(s) but still record high quality video so it can fit on my 16 GB memory card?

Last question, my Canon lacks a mic connection. Is there a cheap workaround to still capture good sound quality with a lapel mic?

Thank you so much.

Terfyn

Are you sure that your Canon will run for 2 hours without overheating? (A problem with many DSLRs recording video)
Your User Manual should give you recording times for the Canon. (depending on the quality setting) but a 64Gb SDXC card should give you some comfort room.
There are many reasonably priced hand held audio recorders on the market but you will have to sync the audio to the video in post production. My own choice is Tascam.